i would not recommend azden. i have had two wireless which both broke with normal use. one of them was only used three to four times, now it just gives me a horrible sound/noise.
i have had good expience with a radio shack wired lavalier mike. cost about $25.usd
Do they have to be wireless? If not check out http://www.core-sound.com. I've always gotten excellent service from the owner, Len, and he has quality mics for all budgets.